The Unites States has announced it is suspending some assistant programmes to Cambodia over its concern with “setback to democracy” in the country.
Last year the country’s main opposition party was dissolved and its leader was charged with treason.
On Monday, the ruling party said it had won every seat in a Senate election.
The result has been questioned by international groups and the European Union has already threatened economic sanctions in response. In statement on Wednesday, the US government announced the cuts saying: “American taxpayer funds are not being used to support anti-democratic behaviour.”
The US said it had spent more than $1bn (£720m) supporting Cambodia as a “committed development partner” over the last 25 years, but said recent events had caused “deep concern”.
It said the suspension would affect military assistance and some treasury programmes, but it would continue to finance projects supporting the Cambodian people directly, in areas such as health, mine clearance and agriculture.
Reports say the aid money being cut amounts to about $8.3m.
The Cambodian government, which has moved away from the West and closer to China in recent years, has yet to respond to the latest announcement.
Mu Sochua, a former deputy leader of the now dissolved Cambodia National Rescue Party (CNRP), welcomed the move.
She told reporters that Cambodia had become a “one-party, one-man state”, and called for all direct foreign aid to the government to be suspended.
The Trump administration had already announced visa restrictions on Cambodian government members in December.
Prime Minister Hun Sen has ruled the country for 33 years and has long been accused of using the courts and security forces to intimidate opponents and crush dissent.